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powerpc/512x: try to free dma descriptors in case of allocation failure

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Currently completed descriptors are processed in the tasklet. This can
lead to dead lock in case of CONFIG_NET_DMA enabled (new requests are
submitted from softirq context and dma_memcpy_to_iovec() busy loops until
the requests is submitted). To prevent this we should process completed
descriptors from the allocation failure path in prepare_memcpy too.

Signed-off-by: Ilya Yanok <yanok@emcraft.com>
Cc: Piotr Ziecik <kosmo@semihalf.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This commit is contained in:
Ilya Yanok 2010-10-27 01:52:58 +02:00 • committed by Grant Likely
parent ba2eea251f
commit a276991357
1 changed files with 45 additions and 34 deletions
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79
drivers/dma/mpc512x_dma.c
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@ -328,19 +328,55 @@ static irqreturn_t mpc_dma_irq(int irq, void *data)
return IRQ_HANDLED; return IRQ_HANDLED;
} }
/* DMA Tasklet */ /* proccess completed descriptors */
static void mpc_dma_tasklet(unsigned long data) static void mpc_dma_process_completed(struct mpc_dma *mdma)
{ {
struct mpc_dma *mdma = (void *)data;
dma_cookie_t last_cookie = 0; dma_cookie_t last_cookie = 0;
struct mpc_dma_chan *mchan; struct mpc_dma_chan *mchan;
struct mpc_dma_desc *mdesc; struct mpc_dma_desc *mdesc;
struct dma_async_tx_descriptor *desc; struct dma_async_tx_descriptor *desc;
unsigned long flags; unsigned long flags;
LIST_HEAD(list); LIST_HEAD(list);
uint es;
int i; int i;
for (i = 0; i < mdma->dma.chancnt; i++) {
mchan = &mdma->channels[i];
/* Get all completed descriptors */
spin_lock_irqsave(&mchan->lock, flags);
if (!list_empty(&mchan->completed))
list_splice_tail_init(&mchan->completed, &list);
spin_unlock_irqrestore(&mchan->lock, flags);
if (list_empty(&list))
continue;
/* Execute callbacks and run dependencies */
list_for_each_entry(mdesc, &list, node) {
desc = &mdesc->desc;
if (desc->callback)
desc->callback(desc->callback_param);
last_cookie = desc->cookie;
dma_run_dependencies(desc);
}
/* Free descriptors */
spin_lock_irqsave(&mchan->lock, flags);
list_splice_tail_init(&list, &mchan->free);
mchan->completed_cookie = last_cookie;
spin_unlock_irqrestore(&mchan->lock, flags);
}
}
/* DMA Tasklet */
static void mpc_dma_tasklet(unsigned long data)
{
struct mpc_dma *mdma = (void *)data;
unsigned long flags;
uint es;
spin_lock_irqsave(&mdma->error_status_lock, flags); spin_lock_irqsave(&mdma->error_status_lock, flags);
es = mdma->error_status; es = mdma->error_status;
mdma->error_status = 0; mdma->error_status = 0;
@ -379,35 +415,7 @@ static void mpc_dma_tasklet(unsigned long data)
dev_err(mdma->dma.dev, "- Destination Bus Error\n"); dev_err(mdma->dma.dev, "- Destination Bus Error\n");
} }
for (i = 0; i < mdma->dma.chancnt; i++) { mpc_dma_process_completed(mdma);
mchan = &mdma->channels[i];
/* Get all completed descriptors */
spin_lock_irqsave(&mchan->lock, flags);
if (!list_empty(&mchan->completed))
list_splice_tail_init(&mchan->completed, &list);
spin_unlock_irqrestore(&mchan->lock, flags);
if (list_empty(&list))
continue;
/* Execute callbacks and run dependencies */
list_for_each_entry(mdesc, &list, node) {
desc = &mdesc->desc;
if (desc->callback)
desc->callback(desc->callback_param);
last_cookie = desc->cookie;
dma_run_dependencies(desc);
}
/* Free descriptors */
spin_lock_irqsave(&mchan->lock, flags);
list_splice_tail_init(&list, &mchan->free);
mchan->completed_cookie = last_cookie;
spin_unlock_irqrestore(&mchan->lock, flags);
}
} }
/* Submit descriptor to hardware */ /* Submit descriptor to hardware */
@ -587,8 +595,11 @@ mpc_dma_prep_memcpy(struct dma_chan *chan, dma_addr_t dst, dma_addr_t src,
} }
spin_unlock_irqrestore(&mchan->lock, iflags); spin_unlock_irqrestore(&mchan->lock, iflags);
if (!mdesc) if (!mdesc) {
/* try to free completed descriptors */
mpc_dma_process_completed(mdma);
return NULL; return NULL;
}
mdesc->error = 0; mdesc->error = 0;
tcd = mdesc->tcd; tcd = mdesc->tcd;